Sometimes they start just a few hours after your last dose of the opiate, but usually they hit you between 6-12 hours after your last dose. Withdrawal symptoms can include irritability, sleeplessness, and increased appetite. You may also notice watery eyes, a runny nose, yawning; perhaps you start sweating or have trouble sleeping (insomnia). You may often feel restless, irritable, notice a loss of appetite, body aches, severe abdominal pain, nausea and vomiting, their website